The disclosed invention is directed generally to center high mounted stoplights for vehicles, and more particularly to a stoplight lens that efficiently meets the required brightness and angular coverage of a center high mounted stoplight.
Present federal regulations require center high mounted stoplights (CHMSLs) in addition to the standard stoplights mounted in the rear portion of an automobile. The high mounted stoplights are intended to maximize the visibility of the automobile braking indicators to drivers following the braking vehicle, and are commonly mounted on the rear window of an automobile.
CHMSLs have commonly been implemented as a standard lenticular colored lens, an illuminating incandescent bulb, and a reflector. In some implementations, the components of a CHMSL are enclosed in a housing that is typically secured adjacent the top or bottom of an automobile rear window, while in other implementations the components of a CHMSL are integrated into automobile body parts such as rear decks, spoilers, roofs.
An important consideration with CHMSLs is the complexity in meeting governmental luminous intensity and angular coverage requirements while utilizing a light source of minimum power. The luminous intensity and angular coverage requirements generally include a quantitative aspect that defines luminous intensity over a defined central angular region, and a qualitative aspect that requires visibility over a horizontal angular region that is greater than the horizontal component of the defined central angular region. Essentially, the regulations require a brighter region generally in the center of the entire angular field of coverage. The luminous intensity and angular coverage requirements can be met by utilizing relatively simple lenses, but much of the light output of the lenses would be in excess of the luminous intensity and angular coverage requirements, which increases the required power of the light source.